The trickery lies in a set of keys built into the hardware that WinPho7 looks for and compares against. If you try to access Xbox, Marketplace, Windows Live, or Zune on a version of the OS that doesn’t match your hardware key, then you’ll be greeted with the screen shown here.

In addition to this, anyone found modifying the phone to fudge with their Xbox achievements or run pirated games will be perma-banned from Xbox Live, much like MS did to Xbox 360 hackers back in 2008.

Now — also like on Windows 7 or Office — these checks aren’t impossible to circumvent, but the link to hardware, as well as the risk of cocking up your Xbox Live account, will make this a wily beast to overcome.

In the mean time, anyone desperate for a custom ROM should probably stick to the well-established hacking grounds of Android or iOS.